"That was a project that lived for so short a time, and such a long time ago, I would look at that as an impossibility," Fillion tells HitFix of the possibility of making a "Serenity 2." "Joss Whedon made a movie of it -- something I also considered an impossibility. So I look at that and think, 'Where is the hope?' But knowing Joss Whedon, I try not to underestimate that man."

With projects like the "Veronica Mars" movie getting a successful Kickstarter and "Arrested Development" being brought back for a fourth season after seven years, it doesn't seem like much of a stretch to assume "Firefly" could be resurrected with a new movie or TV season as well, especially since Whedon has remained such close friends with his cast. It's unclear what exactly is causing Fillion to say that the dream of a "Serenity 2" won't become a reality, but it's likely Whedon's busy schedule.

Whedon is working on "S.H.I.E.L.D." and developing "The Avengers 2," and is pretty much exclusively dedicated to Marvel until "The Avengers 2" comes out on May 1, 2015. Even "Dr. Horrible 2" was bumped until after Whedon's commitment to "The Avengers 2" is complete, which means that, at its earliest, a "Firefly" reunion wouldn't be able to happen until after 2015. It seems like that Science Channel reunion will be all we're getting of the Serenity crew for the time being, but as Fillion notes, if anyone can do the impossible, it's Joss Whedon.